Making gifs is crazy fun.
From the editor, load a level, bop around in it a bit, and then press ⌘/Ctrl+k, then BE PATIENT!. Sooner or later BAM a shiny animated GIF along with a download link should appear in the console, like this:
It's not the fastest generator in the world, and its speed depends on the length of the animation and the resolution of the game-screen in the editor.
However it does now have mouse support.